Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of a first image in a sequence for a display screen or portion thereof with transitional graphical user interface showing my new design.

FIG. 2 is a front view of a second image thereof.

FIG. 3 is a front view of a third image thereof.

FIG. 4 is a front view of a fourth image thereof.

FIG. 5 is a front view of a fifth image thereof.

FIG. 6 is a front view of a sixth image thereof; and,

FIG. 7 is a front view of a seventh image thereof.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-7. The process or period in which one image transitions to another image forms no part of the claimed design.

The outer perimeter illustrated by a pair of broken lines depicts a display screen or portion thereof and forms no part of the claimed design. The remaining broken lines illustrate portions of the graphical use interface and form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 